Change IP to alias in customers web browser

I have a proprietary java based web application that is putting the host IP address in the customers web browser. Is there any way to modify a tomcat config file to replace the IP with the alias? It is in two places in the URL. We are currently using a reverse proxy to redirect public traffic to the alias but something in tomcat or the application itself is pushing the IP address to the browser once it hits the web server. I have looked at the server.xml and web.xml but am having difficulty determining exactly what to do. FYI if there is something below a "programing greenhorn" that's me!

When you say that the application is "putting" the IP address into the URLs it generates, do you mean that the application itself actually generates absolute URLs in that form?

(Based on your self-assessment, you didn't write this application, right? So you would have to track down the programmers and ask them.)

If the application is generating the URLs like that, then Tomcat can't do anything about it. But it's possible that the application is just generating relative URLs, in which case it might be something to do with this reverse proxy you mentioned, and you might be able to do something in the configuration of the reverse proxy or the Tomcat server. Exactly what, I don't know, but you have to get the first question answered before you ask that one.